The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
Multiple input multiple output (MIMO) communication systems are currently receiving a lot of attention. MIMO systems can be used either to mitigate the effects of channel fades or to deliver high bit rates.
A basic paradigm of a turbo receiver is an iterative interconnection of the Soft input soft output (SISO) detector and a SISO decoder. The SISO decoder calculates log-likelihood ratio (LLR) values for input bits, including both systematic and parity bits when a turbo code with systematic component codes are used. For SISO detection purposes, LLR bit values from a decoder need to be mapped into soft symbol values and further into soft chip values by probabilistic bit-to-symbol mapping and spreading operations.
In general, a plurality of possibilities to perform SISO detection exists. One possibility is a minimum mean square error (MMSE) chip equalizer followed by a correlator which is matched to spreading codes of a desired signal and a demodulator which performs the probabilistic symbol-to-soft bits mapping.
High Speed Packet Access, HSPA, is able to provide high data rate transmission to support multimedia services, for example. HSPA includes High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA).